1. Field of the Invention
The invention relates to a remote control device, more particularly to a learning-type remote control device which is capable of detecting both the carrier frequency and the control code in a remote control signal that is transmitted by another remote control device, and which is capable of generating remote control signals of different carrier frequencies.
2. Description of the Related Art
Remote control devices, such as those used in the control of garage doors and car alarms, have become an indispensable part of our daily lives. Therefore, there is always a need to make back-up remote control devices in order to avoid replacement of the entire remote control system in the event that a remote control device has been misplaced.
U.S. Pat. No. 5,237,319 discloses a remote control device having a learning function in which a remote control signal transmitted from another remote control device is received to perform learning and to transmit a new remote control signal on the basis of the learning. When making a copy of a target remote control device, the learning-type remote control device is capable of learning a control code that is present in a remote control signal from the target remote control device. Thus, the learning-type remote control device is more convenient to program than one having no learning function. However, the remote control signal of a remote control device further includes a carrier signal portion that is modulated by the control code. Presently, a separate instrument is needed to measure the carrier frequency of the target remote control device, and to set the conventional learning-type remote control device to the measured carrier frequency before a copy of the target remote control device can be made.
Measurement of the carrier frequency of the target remote control device, and setting of the conventional learning-type remote control device to the measured carrier frequency are time-consuming tasks that cannot be accomplished by the consumer without using a separate instrument. Moreover, the conventional learning-type remote control device can only generate remote control signals of the same carrier frequency, thereby limiting its utility.